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Old 08-21-2012, 03:11 PM   #1
ironmanco
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Default 1995 Legacy SBF #2 keeps blowing - won't start

As the title says, I have a 1995 sub legacy that will crank but won't start. I keep blowing SBF #2 which I "think" cover the fuel pump as well as many other things. I'm thinking a grounding issue but don't really know where to start on this. Any help would be appreciated.
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Old 08-22-2012, 05:13 AM   #2
Cougar4
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Here is a list of places that fuse SBF-2 supllies power to:
Engine control module
Fuel pump relay
Main relay
OBD-II service connector

The main relay ties to a lot of engine devices. Check to see of any of the O2 sensor wires have made contact to the exhaust system and melted the wiring. Chances are the short is in the engine compartment area.

You could remove the relays to see if the short is on the other side of them. You could disconnect the ECU and see if the problem is with it. There is the also the possibility that a mod has been added to the wiring and it has a problem.

It would be helpful to have a meter to measure the resistance of the fuse wire on the protected side of the fuse connection. By watching for a change in the resistance to ground you will be able to see when the short is cleared and not ruin a bunch of fuses. You could also install a brake light bulb in place of the fuse to limit the current. When the short is removed the light will dim.

Last edited by Cougar4; 08-22-2012 at 05:21 AM.
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Old 08-24-2012, 02:21 AM   #3
ironmanco
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After removing the fuel pump relay, obd service connector and ecm and then a bunch of other things that are down stream from the main relay - I couldn't for the life of me figure out what was causing the short. With a multimeter in hand I got it down to the fuel injectors but couldn't find a short. After almost two days of working this I finally gave up and let my bud at the shop have a look. Turns out that the wiring harness that goes under the intake manifold had shorted itself to ground. He had to remove the entire intake mainfold just to get to the short and then clean, splice and re-insulate the wires. Though it cost me in labor to do that, I'm glad to know that I probably would have NEVER found that one.
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Old 08-24-2012, 03:41 AM   #4
Cougar4
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Glad you found the problem, though it wasn't easy. Thanks for the update.
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Old 09-12-2012, 11:09 AM   #5
98legacygtslam
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I am having the same issue on my 99 lgt. I let my friend take a look at it and he did I let my friend take a look at it and he did jump the fuse with the wire that ended up smoking.since then I have no spark and my fuel pump won't prime when I turn the key on. I believe I have found theshort underneath the sending unitcap . I have since replaced the crank sensor cam sensor coil igniter and ECU ***********and still no spark or fuel prime unless I jumped the fuel pump relay please help
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Old 09-12-2012, 03:17 PM   #6
ironmanco
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Remember the short can be ANYWHERE along the wiring on this circuit - not necessarily right at a sensor location.
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Old 09-12-2012, 07:56 PM   #7
Cougar4
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Make sure power is getting to the areas you mentioned. There may be a problem after the Main Relay and also in the wiring. You may have to replace some bad wiring. I suggest you get a factory wiring manual if you don't have one. That and a meter will help you a lot in finding the problem.
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Old 09-15-2012, 02:12 AM   #8
98legacygtslam
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But here's the kicker, I found a pinched wire under where the sending unit bolts to the tank, and now the fuse isn't popping but still no spark when cranking or fuel prime on koeoff. Could the ignition switch be partially burnt? As in it still cranks the engine but won't send the ecu a reference signal to turn on?
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Old 09-15-2012, 02:51 PM   #9
Cougar4
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Power to the ECU and fuel pump are provided by relays that are tied to power via the fuse. You need to check them and make sure they are working.
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Old 09-21-2012, 02:45 AM   #10
98legacygtslam
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Do you, or anyone happen to know what relays I should check or replace? And locations of those certain relays? I just replaced the fuel pump relay and the other two cylindrical relays located right beside it. I also replaced the ignition switch and The sbf isn't blowing anymore but I'm still getting no spark or fuel prime. Does anyone happen to have ground locations for a 99 legacy gt special edition? That's the only thing I can think of other than the relays I will check when I get some kind of guidance on their locations... p.s. I plugged my code reader in and pulled 4 codes 1st was po463 2nd was po187 and then they repeated to total up to 4 codes total. But like I said still no spark or fuel prime. Please help I've been rid in a street trail bike to work 30 miles one way. Needless to say late September mornings in pa are less than favorable riding weather lol
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Old 09-21-2012, 04:37 AM   #11
Cougar4
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I have a drawing for a '95 Legacy and it may be the same as yours is. It shows the Main and fuel pump relays are under the dash, on the left side, way up near the top. Look for a brown socket for the Main Relay and a black one for the fuel pump relay. Power from SBF-2 comes to both those relays on a red wire. See if you have voltage on that wire going to the relays. The same red wire goes to the ECU on pin 42. The wire may have been damaged somewhere along the line.
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